Code for redirecting an HTML page without an extension using an .htaccess file results in a 404 error

Question

I'm trying to redirect an HTML page to a WordPress page which has no extension. The result of redirecting example.com/fa/home.html to example.com/fa/ is a 404 page not found. As you can see they're both in a sub-directory.

I've tried many approaches, whether manually or through cPanel to redirect those URLs. Note that I'm using a Nginx web server.

When I try to redirect another URL like example.com/en/home.html which is NOT in the /fa directory, it will successfully redirect. I have an .htaccess file in the root folder and one in the /fa directory. I deleted everything in the .htaccess file in the /fa directory and only left the default index page rule, but still no luck.

The .htaccess code in the root directory is:

RewriteEngine on
DirectoryIndex Portal.html

RewriteEngine On
RewriteCond %{HTTP_HOST} ^mscaspian.com$
RewriteRule (.*) http://www.mscaspian.com/$1 [R=301,L]

RewriteCond %{HTTP_REFERER} !^http://mscaspian.com/.*$      [NC]
RewriteCond %{HTTP_REFERER} !^http://mscaspian.com$      [NC]
RewriteCond %{HTTP_REFERER} !^http://www.mscaspian.com/.*$      [NC]
RewriteCond %{HTTP_REFERER} !^http://www.mscaspian.com$      [NC]
RewriteRule .*\.(jpg|jpeg|gif|png|bmp)$ http://www.mscaspian.com [R,NC]

ErrorDocument 404 /404.html 

And the code in the /fa directory is:

 DirectoryIndex index.html index.htm index.php

 <IfModule mod_rewrite.c>
 RewriteEngine On
 RewriteBase /fa/
 RewriteRule ^index\.php$ - [L]
 RewriteCond %{REQUEST_FILENAME} !-f
 RewriteCond %{REQUEST_FILENAME} !-d
 RewriteRule . /fa/index.php [L]

Answer 1

I believe this will start you off right: I don't believe the rewrite rule is necessary, when the default page for WordPress is index.php

Options +FollowSymLinks
RewriteEngine on

Redirect 301 ^/home.html http://www.mscaspian.com/fa

---

Update

Localizing WordPress
List of Localization Plug-Ins

I am not affiliated in any way to the list of plug-ins above, just Googled for:

localize wordpress content

---

Update 2
List of Common Redirects

As per your comment, you need to add a redirect rule for all pages, as a separate line, Ex:

Redirect 301 ^/about.html http://www.mscaspian.com/fa/about
Redirect 301 ^/contact.html http://www.mscaspian.com/fa/contact

As I stated earlier, since the default page is index.php. and all these pages are handled by index.php, redirecting to the "Pretty URL" is perfectly legal, only if you have the rules for Pretty Permalinks Enabled, before the redirects.